well its on the thread of all 4 the sparkplugs and none are on the plug wire. so its either the pcv pipe that is clogged or the piston ring is leaking?. i've check on others 240 sites too and a few of them said it could be the valve cover o ring seal or something. how hard is it to fix the piston ring or the valve thingy? oh and it doesnt smoke. it just idle like crap :\ only idle when its warmed.